Metaphorical evolutionary arms races, such as those between prey and their predators, are well-studied and important examples of coevolution (see, e.g., Geerat J. Vermeij's book Evolution and Escalation: An Ecological History of Life). The participants in these races must compensate for newly evolved defenses and counterdefenses by evolving new capabilities. Critical examples often come from studies of insects, in part because the multitude of possibilities is extensive as befits such a diverse group. The natural history of insects always tantalizes, offering us unexpected glimpses into a world seldom recognized except by keen observers. Vintage writing about insect natural history—seen in Life on a Little Known Planet by Howard E. Evans, Niko Tinbergen's Curious Naturalists, and May R. Berenbaum's monthly columns in The American Entomologist (collected in her book Buzzwords)—represents some of the best examples of the genre. In How Not To Be Eaten: The Insects Fight Back, author Gilbert Waldbauer successfully frames the natural history of insect predator-prey interactions against the understanding that predation has an inordinate influence on insect adaptation. This is important, given that insects play significant and central roles in natural food webs and ecosystem function.
The book emphasizes the incredible diversity of solutions that insects have displayed through evolution to ward off the continual challenges that face them. To illustrate such a diverse array of predator-prey interactions, Waldbauer organizes his book according to the many ways that prey can thwart detection or reduce predators' capture efficiency—fleeing and hiding, mimicking or appearing to be something not considered edible, inducing startle responses, reducing risk through safety in numbers, maneuvering with defensive tactics, and warning predators by using chemical defense signals. To complete the continuously evolving cycle, Waldbauer also describes predator countermeasures that arise to combat these prey defenses.
How Not To Be Eaten is engaging in its descriptive and wide-ranging examples. Waldbauer's writing highlights an understanding of the detailed natural history of each species, and it also focuses on the multiple kinds of approaches taken by investigators to devise and test hypotheses of how insect prey reduce their predation risk. Each chapter provides appropriate and interesting case studies to illustrate its main points, and the author's chosen examples are a blend of contemporary studies mixed with important classics. Both the scientific audience and those who simply appreciate organismal diversity and who are keenly interested in the natural world will enjoy this book.
Each chapter section describes how a specific adaptation might work in certain instances. In each of these cases, the author surveys previous studies to inform the reader about the general scope of evidence documenting how the mechanism in question serves to limit predation risk. Few examples are presented that refute specific hypotheses, but some are acknowledged. One example surprised me: Despite wide-spread acceptance of its efficacy, there is no evidence offered for or against the adaptation of disruptive coloration to reduce predation risk as a successful tactic in natural systems. In most cases, however, affirmative studies dominate the text in order to make the point that successful adaptations by insects are manifested in the many types of their effective defenses.
Despite the range of fascinating examples described in the book, I was somewhat disappointed in one aspect: The book does not offer a developed presentation of the underlying evolutionary dynamics associated with these complex relationships. After all, most traits are the result of integrated morphological and behavioral features that match fairly closely in a finely tuned adaptation. Although Waldbauer presents some evidence that even rudimentary change in antipredator traits confers fitness benefits that lead to the evolution of more complex combinations, such discussions are dispersed casually throughout the book, thus diluting a critical message.
What is missing, for the most part, are theoretical contexts and hypotheses of the more complex ecological and evolutionary dynamics that are critical for understanding the evolution of predator-prey adaptations and their ecological consequences. For example, the relative roles of density- and frequency-dependent selection and their significance to the evolution of mimicry systems are not explained directly. Recent studies on sensory bias, which have been focused on constraints on predators’ perceptual capabilities (e.g., sensitivities to different wavelengths of light), and the resulting evolution of antipredator traits are also not included. Lip service is given to the role of natural selection in the evolution of many interesting interactions, but the details about how natural selection acts in specific cases are not well developed overall.
Although evolutionary dynamics are critical to fully understanding the adaptations included in the book, these concerns are fortunately not a major distraction, because the examples are so interesting. Besides, this was not a major goal of the author, and my desire for more detail attests to the interest generated throughout by his examples.
With case studies that combine natural history, observation, and some manipulation to illustrate the diverse approaches used by insect prey to reduce predation risk, Waldbauer succeeds in highlighting the intense and captivating evolutionary arms race taking place among insects. Some examples described in this book are already part of the public consciousness, and other, lesser-known examples are now presented for all to appreciate. In How Not To Be Eaten, Waldbauer provides not only a life history but a roadmap for developing new fascinating studies of interactions between insect prey and their predators. Moreover, the book gives us motivation to spend a little more time wandering out into the world and taking a closer look at insects as they fight back in an intense, ongoing battle.
